SHORT-TERM EFFECTS OF INTRAARTERIAL PROPIONYL-L-CARNITINE ON ISOLATEDCANINE HIND-LIMBS

Treatment with propionyl-L-carnitine has been shown to increase the wa lking capacity of patients with peripheral vascular disease but the me chanisms responsible for the effect are unknown. To study the effects of propionyl-L-carnitine on musculocutaneous vascular beds and the rel ated mechanisms, a preparation of constant-pressure blood-perfused dog hind-limb was used. Since the propionyl-L-carnitine solution had a pH less than 4 the contralateral limb simultaneously received acidified saline. The substances were injected into the perfused arteries in 2 m inutes or in 20 minutes, and the cumulative dose of propionyl-L-carnit ine was 20 mg/kg for each administration. The preparation was well sui ted for this study, because there were no major systemic effects of pr opionyl-L-carnitine, nor signs of cross-circulation between the isolat ed limbs. Propionyl-L-carnitine increased flow by 130% in 2 minute inf usions and by 49% in 20 minute infusions. Acidified saline increased f low by 47% in 2 minute infusions and by 34% in 20 minute infusions. Th e difference between propionyl-L-carnitine and acidified saline was si gnificant in 2 minute infusions. The 2 minute infusions of propionyl-L -carnitine increased venous PO2 by 34% and PCO2 by 22% while PH decrea sed by 0.07. The 20 minute infusions of propionyl-L-carnitine increase d PO2 by 22% and PCO2 by 24% while PH decreased 0.10 units. Acidified saline increased only venous PO2 in 2 minute infusions (16%). Calculat ed oxygen consumption of the perfused limbs increased in 2 minute infu sions of propionyl-L-carnitine, but not significantly. It was conclude d that propionyl-L-carnitine has a direct vasodilator effect in muscul ocutaneous vascular beds at high doses and probably enhances tissue me tabolism.